Laser scanning units are known comprising a laser diode for generating a laser beam, a rotating polygonal mirror for reflecting the laser beam along a scan line on a photoconductive (PC) drum, and post-scan optics comprising at least one fΘ lens and at least one stationary mirror positioned between the rotating mirror and the PC drum. To prevent dust and like contamination from reaching the rotating polygonal mirror within a housing of a laser scanning unit, the housing is typically sealed to prevent air from passing into the housing. U.S. Pat. No. 5,953,042 discloses structure to seal a space between a housing cover and a lens. It is also known to use V-shaped polyester film strips to seal gaps between a lens and a cover of a laser scanning unit housing. The cover includes walls defining a lens-receiving opening. The film strips extend along longitudinal side portions of the lens and longitudinal walls of the cover defining a portion of the lens-receiving opening. The polyester film strips are die cut into rectangular blanks, formed into a V-shape and adhesively secured to the longitudinal cover walls. An edge of each strip opposite an edge adhesively secured to a cover wall engages a corresponding side portion of the lens. The strip edge is maintained in position against the lens side portion by a spring force, inherent within the V-shaped strip, acting on the strip edge contacting the lens.